1. Field of the Invention
The present inventive method relates to a method and an arrangement for reducing a number of measured values of a technical system.
2. Description of the Related Art
A technical system, for example a process engineering plant, supplies a large quantity of measured values per unit time, using different measured-value pickups (sensors). In the course of a number of days or weeks, a quantity of data accumulates which requires a correspondingly high computational power to process it. If the measured values are to be used to adapt or reset the technical system, operations are often necessary whose complexity admits only some of the measured values. It is then a great disadvantage to select a specific number of measured values arbitrarily from the quantity of all measured values and to process them further, since measured values with low significance, for example measured values with a high degree of interference, have a considerable influence on the overall result and falsify the latter considerably.
The object of the invention is to specify a method and an arrangement for reducing measured values, it being ensured that the remaining measured values have a high significance with regard to their description of the technical system. In order to achieve the object, a method of reducing a number of measured values of a technical system is specified, in which the measured values are divided into classes in accordance with predefined criteria. The measured values in a class are assessed and those measured values whose assessment lies below a predefined first threshold value are screened out.
Screening out the measured values results in a reduction with regard to the number of measured values. A considerably reduced number of measured values is thus available for further processing. The further processing can be carried out with a lower computational outlay as compared with the non-reduced number of measured values.
In one embodiment, the classes themselves are also assessed. In particular, a class whose assessment lies below a predefined second threshold value can be screened out. This results in an additional reduction in the number of measured values.
In another embodiment, one criterion for the division into classes consists in that, for each class, measured values relating to a predefinition of setting parameters of the technical system are determined. Typically, the technical system is set using a predefined number of setting parameters and after the setting has been carried out, there follows a (mostly time-delayed) reaction of the system to the setting parameters (transient response, transient process of the system). After the setting operation, a specific quantity of measured values which can be associated with the transient process are therefore picked up, measured values which are associated with the predefined set of setting parameters continuing to accumulate after the transient process has concluded (transition to steady-state operation). By adjusting the setting parameters, a new class is determined. All the measured values which respectively accumulate after an adjustment to the setting parameters belong in their own class. Another development consists in that measured values within a class which can be associated with the respective transient process are screened out. In addition, erroneous measured values can be screened out. In many cases, the setting of large technical systems depends on long-term, steady-state operation. Measured values which relate to the transient process (of short duration in comparison with the steady-state operation after the transient process has concluded) are expediently screened out, since measured values for the steady-state operation are falsified by them. In particular within the context of modeling the technical system, the measured data about the steady-state behavior of the technical system are of interest.
One refinement of this embodiment consists in reducing the number of measured values in a class in that at least one representative value for the measured values in the class is determined. Such a representative value may be:
a) an average (e.g. a sliding average) of the measured values of the class,
b) a maximum value of the measured values of the class,
c) a minimum value of the measured values of the class,
d) a median.
In the case of variant (d), one advantage resides in the fact that it is always possible to determine a value which is actually present, while the average (a) does not itself occur as a value.
Depending on the application, a suitable selection for determining the representative value of a class may be made.
An entire class with measured values can be screened out if said class contains less than a predefined number of measured values.
Another refinement consists in that those measured values are screened out which differ from a predefinable value by more than a predefined threshold value.
The predefinable value can be an average of all the measured values of the class or a measured value to be expected in response to the respective setting parameters of the technical system.
A development consists in that the measured values which are reduced in number are used for the simulation and/or the draft design of this or another technical system.
The draft design of the technical system can in this case comprise both adaptation and redrafting of this or another technical system.
In addition, within the context of the simulation, the behavior of the technical system can be checked by using the reduced number of measured values, with the objective of altering the system for developing a new system with altered predefinitions.
In addition, in order to achieve the object, an arrangement for reducing a number of measured values of a technical system is specified which has a processor unit, which processor unit is set up in such a way that the measured values can be divided into classes in accordance with predefined criteria. Measured values in a class can be assessed, measured values whose assessment lies below a predefined first threshold value are screened out.
This arrangement is particularly suitable for carrying out the method according to the invention or one of its developments explained above.